This works in Safari and Chrome for me, but may also work in other browsers, maybe with little modifications.

ExecuteJavaScript "document.body.style.zoom='200%';"

If you run this in your webpage, the content is zoomed to 200%. I think this is useful to offer people buttons like smaller, middle and bigger where they can zoom the content.
Or with some math to make the webcontent fit the screen on a large window.
21 02 13 - 16:38